A bizarre headed own goal by Gabriel Tamas and a scorching drive by David Hoilett took Blackburn to 31 points. The next nine clubs are separated by only five points, including West Brom in 15th place, three points above the relegation zone.
GEAR:Save money on Blackburn shirts courtesy of Kitbag. Free delivery on orders over £50
Manchester United, who thrashed Birmingham City 5-0 on Saturday, lead with 48 points, two ahead of Arsenal. Manchester City are third on 45 with champions Chelsea, who visit Bolton Wanderers on Monday, fourth on 38.
In a rare Sunday when none of the big four were in action, Blackburn hogged the limelight in the week they extended the contract of manager Steve Kean to 2013.
They dominated from the start and only good goalkeeping by Boaz Myhill kept them at bay.
However, he was left helpless after 41 minutes when defender Gabriel Tamas, attempting a straightforward clearing header, sent the ball in the opposite direction and into his own net.
More poor defending just after the restart gave Hoilett time and space on the edge of the box and the 20-year-old Canadian lashed a fierce drive beyond Myhill.
West Brom improved and their best chance should have come midway through the half when Peter Odemwingie was brought down in the box, only for the free-kick to be given outside.
"It was clearly a penalty, it could have got us back into the game but we don't seem to be getting clear decisions in the last couple of weeks," West Brom boss Roberto Di Matteo told Sky Sports after his sixth defeat in seven games.
"We have to work on our mistakes and improve and we need to get some points under our belt."
Kean, who took over after the controversial sacking of Sam Allardyce in December, was delighted with his side's attitude.
"The togetherness of the team, the spirit, the atmosphere around the training ground has been fantastic, that tightness of the group really pleased me," he said.
